Process for making carboxymethyl cellulose carriers for bluing and fluorescers

ABSTRACT

A PROCESS FOR PRODUCING DYED ALKALI METAL CARBOXYMETHYLCELLULOSE VIA A SLURRY PROCESS WHEREIN CELLULOSE IS DYED AFTER ADDING IT TO AN ALKALI HYDROXIDE-SOLVENT-WATER MIXTURE AND PRIOR TO RREACTING IT WITH MONOCHLOROACETIC ACID.

3,734,759 PROCESS FOR MAKING CARBOXYMETHYL CELLULOSE CARRIERS FOR BLUINGAND FLUORESCERS Burton H. Gedge III, Wyoming, Ohio, assignor to TheProcter & Gamble Company, Cincinnati, Ohio No Drawing. Filed May 20,1971, Ser. No. 145,576 Int. Cl. C08b 27/76 US. Cl. 106-193 4 ClaimsABSTRACT OF THE DISCLOSURE A process of producing dyed alkali metalcarboxymethylcellulose via a slurry process wherein cellulose is dyedafter adding it to an alkali hydroxide-solvent-water mixture and priorto reacting it with monochloroacetic acid.

BACKGROUND OF THE INVENTION Slurry processes for makingcarboxymethylcellulose are well known in the art. U.S. Patent 2,135,128issued to Edward Boaden Thomas et al. on Nov. 1, 1938 and US. Patent2,517,577 issued to Gene D. Klug et al. on Aug. 8, 1950 both describeslurry type processes for producing carboxymethylcellulose. However,these processes do not provide a dyed carboxymethylcellulose.

A method for obtaining dyed cellulose ethers includingcarboxymethylcellulose is described in US. Patent 2,448,- 515 issued toWilliam B. Carroll, Jr. on Sept. 7, 1948. This patent describes aprocess for obtaining dyed cellulose ethers by dying the cellulose etherin its natural, solid form and thereby produce a dyed, solid celluloseether which can then be dissolved in an alkali, Col. 1, lines 20-24. Thecellulose ether preferred in this reference is the hydroxy ethylcellulose because in order to practice the invention, the materialshould be insoluble in water and soluble in alkali.Carboxymethylcellulose used in detergent compositions does not satisfythose requirements. The patent further describes the use of the dyedhydroxy ethyl cellulose in the dying of fabrics which is not of concernin the present invention. Should a carboxymethylcellulose be dyed by theCarroll process for use in a detergent formulation, it must be rinsedand dried prior to any use in conjunction with either a detergent slurryor before it is mixed with a granular detergent product to remove excessdye.

A Canadian Patent 692,844 issued to Unilever in 1964 discloses a processfor fixing optical brighteners to carboxymethylcellulose to readilypermit their further transfer to a textile material. However, thispatent merely teaches the use of an already preparedcarboxymethylcellulose.

Thus, carboxymethylcellulose containing dyes or optical brighteners arewell known in the art. However, the economical and convenient method ofproducing such dyed or optically brightened carboxymethylcellulose ofthis invention has not been disclosed.

The main object of this invention is to provide an improved and moreeconomical process of producing a carboxymethylcellulose which is dyed.This is achieved by incorporating a critical dying step strategicallyinto a known slurry process for making carboxymethylcellulose withoutcreating additional mass transfer requirements. Another object of thisinvention is to select the dyes which are compatible with the aboveconcepts.

An advantage of this invention is to eliminate a rinsing step which isrequired in all prior art dyed carboxymethylcellulose processes. Thepurpose of the rinsing step has been and is to remove the excess dyefrom the formed carboxymethylcellulose to prevent it from coloring adetergent slurry or staining a granular detergent product United StatesPatent O Patented May 22, 1973 with which it is dry mixed. It has beendiscovered that the separate drying and rinsing steps may be eliminatedif the dye is introduced at a strategic time in the process for makingcarboxymethylcellulose as further described herein.

BRIEF SUMMARY OF THE INVENTION The improved process for producing a dyedalkali metal carboxymethylcellulose comprises mixing an organic solventwith water, adding cellulose which is to be converted to an alkali metalcarboxymethylcellulose to the mixture, subsequently reacting thecellulose, solvent, water mixtures with an aqueous solution of alkalimetal hydroxide, adding the dye to be used, then acidifying the mixtureby adding monochloroacetic acid. This single process achieves bothconversion of and dying of the cellulose to a dyed alkali metal, e.g.,sodium, carboxymethylcellulose.

The dyed alkali metal carboxymethylcellulose can then be filtered andadded to a detergent slurry to be crutched and spray dried.Alternatively, the dyed cellulose can be filtered and dried and directlydry-mixed with a granular detergent composition. The product produced bythis process surprisingly, does not stain either the mixture to becrutched or the already formed granular detergent compositions.

DETAILED DESCRIPTION OF THE INVENTION The process of this invention forobtaining a dyed alkali metal carboxymethylcellulose product iscomprised of the following steps:

\ (2) adding from about 1 to about 20 parts of cellulose to thesolvent-water mixture to form a cellulose-containing slurry;

(3) reacting the cellulose-containing slurry with from about 0.4 toabout 20 parts of an alkali metal hydroxide to form an alkalized slurry;

(4) adding a dye to the alkalized slurry in an amount such that theratio of the dye to the cellulose present in the slurry is in a range offrom about 1:6 to about 1:250 to form a dye-containing slurry; and

(5) reacting the dye-containing slurry with from about 0.4 to 2.5 molesof monochloroacetic acid per mole of cellulose whereby dyed alkali metalcarboxymethylcellulose is formed.

The dyed carboxymethylcellulose has a degree of polymerization of fromabout 20 to about 30,000, preferably to 20,000 and a degree ofsubstitution of from about 0.4 to about 0.9, preferably 0.5 to 0.9.

The product produced by this process can be directly dry-mixed into adetergent composition or added directly to a detergent slurry to becrutched and spray-dried without the benefit of a rinsing step to removeexcess dye stuffs. When the dyed carboxymethylcellulose of thisinvention is added to a detergent slurry before spray drying, it isvirtually impossible to distinguish dyed carboxymethylcellulose granulesfrom the remainder of the detergent granules produced after the slurryis spraydried. Thus, by practicing the present invention, it is possibleto provide a detergent composition containing bluing ingredients oroptical brighteners which are not visible to the naked eye. Such aproduct provides flexibility in the formulation of detergentcompositions.

The organic solvent used in this process can be selected from the groupconsisting of methylacetate, methylethylketone, acetone, dioxane,isopropyl alcohol, tertiary butyl alcohol, and methylene ether, ormixtures of these solvents. In the' practice of the invention, purifiedcellulose, for example, chemical cellulose prepared from wood or cottonlinters as dissolving grade cellulose can be used. While fibrouscellulose can be agitated to form a well dispersed slurry whereincellulose is intimately contacted with chemical reagents, those skilledin the chemical arts will realize that contact is improved by reducingthe size of cellulose particles to achieve greater particle surfacearea. Accordingly, it is preferred to use dissolving grade cellulosecutter ground to permit it to pass through a Tyler Standard screen ofabout 20 to about 60 mesh, but the beneficial results of the presentprocess can be obtained with fibrous cellulose or with cellulosecomminuted to pass screens having still smaller openings than thosementioned above.

The alkali metal hydroxide can be sodium hydroxide, potassium hydroxideor lithium hydroxide, added preferably as an aqueous solution, sodiumhydroxide is the preferred hydroxide.

In the selection of the dye used to practice this invention, threefactors are of importance. First the color desired in the final product,secondly, the dyes substantivity to carboxymethylcellulose, and finally,the ability of the dye to withstand the rigors of the chemical reagentsto which it must be subjected to convert the cellulose tocarboxymethylcellulose. The ratio of the dye to the cellulose in theslurry is in a range of from 1:6 to about 1:250, preferably from 1:10 to1:150.

Dyed carboxymethylcellulose of this invention to be used in a granularlaundry detergent should be blue or optically active to produce a whiteor blue-white appearing wash or both. Suitable and representative dyeswhich are substantive to carboxymethylcellulose and can Withstand thealkali hydroxide solution to which they are initially added and therigors of the addition of monochloroacetic acid used to form a sodiumcarboxymethylcellulose are listed below with references to the colorindex published by the American Association of Textile Chemists andColorists, Lowell Technological Institute, Lowell, Mass. In the case ofthe blue dyes recommended:

C.I. Direct; Blue 15 (Blue) CHQO OCH: 110

S OaNB NaOaS- NBOsS C.I. Direct Blue 1 (Bright greenish blue) C1130 OCH,

0.1 Direct; Blue 25 (Blue) HzN OH H NaOaS HO HO Besides producing dyedcarboxymethylcelluloses the present invention is also useful for makingoptically brightened carboxymethylcelluloses. For such an embodiment, itis only necessary to replace the aforementioned dyes with a suitablechemically resistant optical brightener. Flexibility is provided also byemploying both a dye and an (m ical brightener simultaneously.

The optical brighteners useful in the practice of the invention arethose brighteners whose brightening action is not diminished by thechloroacetic acid used in the slurry process. A satisfactory andrepresentative brightener is marketed under the trade name Tinopal, byGeigy Chemical Corporation. The chemical name of this brightener issodium 4(2H-naphtho(1,2-d)trazol-2-yl)-2- stilbene sulfonate. Forpurposes of this invention the term fiuorescers is synonymous withoptical brighteners and the term dye is used generically to includebluing dyes as well as optical brighteners.

Example I The preferred process of this invention can be practiced asfollows. One hundred 'five pounds of comminuted wood cellulose cut topass a 30-mesh screen containing five pounds of water is introduced intoa reactor. An aqueous acetone solution containing 2,083 pounds ofacetone and 358 pounds of water is simultaneously introduced into thesame reactor. The resulting slurry of comminuted cellulose in aqueousacetone is then vigorously agitated. Next, 108 pounds of an aqueoussolution containing of sodium hydroxide are added over a period of 0.167hour while continuing the agitation. The total liquid to cellulose ratioin the first step reactor is 25 to 1, while the Water to cellulose ratiois about 4.17 to 1 and the acetone to water ratio is about 5 to 1. Thereaction slurry is maintained at a temperature of 25 C., and the slurryis stirred vigorously for 0.25 hour to alkalize the cellulose. Followingthe alkalization period, 1,360 pounds of liquor containing 190 pounds ofwater are removed from the reactor before dropping the resulting slurryof alkali cellulose into a second step reactor. One thousand two hundredtwo pounds of anhydrous acetone are added S 0 Na S OaNa OaNa V S OaNa tothe second step reactor while maintaining vigorous agitation in thereactor. During the second addition of acetone, one pound of Cl. DirectBlue 15 of the following formula:

HzN ()H 01130 a) Ha H O NaOaS SOgNS. M 8

is added to the alkali-cellulose-acetone-water mixture. This representsa ratio of dye to cellulose of about 1:100.

The resulting dye-containing slurry is then treated with 58.4 pounds ofmonochloroacetic acid dissolved in 158 pounds of acetone over a periodof 0.25 hour. The total liquid to cellulose ratio in the second stepreactor is 25 to 1 While the water to cellulose ratio is about 2.7 to 1and the acetone to water ratio is about 10 to 1. The temperature of thevigorously agitated mixture is then raised to 70C. and maintained atthis temperature for 2.5 hours with continuing agitation to etherify thecellulose. At the end of the etherification period, the slurry is cooledto 45 C. and dropped into a separator. In the separator the dyedcarboxymethylcellulose product is separated from the aqueous acetoneslurry and dropped into a dryer. The'resulting dried and dyedcarboxymethylcellulose has a D5. of 0.76 and is noted to be visibly freeof fibers and gels when dissolved in water to a 1% concentration byweight.

The dyed carboxymethylcellulose product of Example I is especiallysuited for use as an anti-redeposition agent and bluing agent indetergent formulations. When added NaOaS 0.1. Direct Blue 1 (Brightgreenish blue) HzN OH CHaO (])CH HO NaOQS 0.1. Direct Blue 25 (Blue) HO(|)H H3 0 0 H3 H 0 NaOaS S OaNa NaOsS In addition to a blue dye selectedfrom the above group, the carboxymethyl cellulose may be optically dyedby adding an optical brightener such as sodium 4(2H- naphtho-( 1,2-d)trazol-2-yl 2-stilbene sulfonate.

The temperatures used in the foregoing process steps can be adjustedeasily by those skilled in the art to take into consideration materialshaving physical properties different from those used in Example I.

Example II Another example of the process of this invention follows. Onehundred five pounds of comminuted wood cellulose cut to pass a 30 meshscreen containing five pounds of Water is introduced into a reactor. Anaqueous acetone solution containing 1,925 pounds of acetone and 358pounds of water is simultaneously introduced into the same reactor. Theresulting slurry of comminuted cellulose in aqueous acetone is thenvigorously agitated. Next, 108 pounds of an aqueous solution containing50% of sodium hydroxide are added over a period of 0.167

hour while continuing the agitation. The total liquid to cellulose ratioin the first step reactor is 25 to 1, while the water to cellulose ratiois about 4.17 to l and the acetone to water ratio is about 5 to 1. Thereaction slurry is maintained at a temperature of 25 C., and the slurryis stirred vigorously for 0.25 hour to alkalize the cellulose. Followingthe alkalization period, one pound of C1 Direct Blue 15 of the followingformula:

is added to the alkali-cellulose-acetone-water mixture.

This represents a dye to cellulose ratio of about 1: 100. The resultingdye-containing slurry is then treated with 58.4 pounds ofmonochloroacetic acid dissolved in 158 pounds of acetone over a periodof 0.25 hour. The total liquid to cellulose ratio in the second stepreactor is 25 to 1 while the water to cellulose ratio is about 4.17 to 1and the acetone to water ratio is about 5 to 1. The temperature of thevigorously agitated mixture is then raised to C. and maintained at thistemperature for 2.5 hours with cont-inning agitation of etherify thecellulose. At the end of the etherification period, the slurry is cooledto 45 C. and dropped into a separator. In the separator l S OsNa O aNathe dyed carboxymethylcellulose product is separated from the aqueousacetone slurry and dropped into a dryer. The resulting dyed sodiumcarboxymethylcellulose is found to have a D8. of 0.55 and is noted to bevisibly free of fibers and gels when dissolved in water to a 1%concentration by weight. The dyed carboxymethylcellulose product isuseful as an anti-redeposition agent and bluing agent in detergentformulations.

A dyed sodium carboxymethylcellulose prepared by this invention whichcontains optical brighteners is useful to provide a surprisinglyeconomical and convenient detergent formula that is opticallybrightened, contains bluing and antiredeposition agents all in a highlydispersed and usable form.

All proportions herein are by weight unless otherwise specified.

What is claimed is:

1. A process for producing dyed alkali metal carboxymethylcellulosewhich comprises:

(1) mixing from about 1 to about 20 parts of an organic solvent selectedfrom the group consisting of methyl acetate, methylethylketone, acetone,dioxane, isopropyl alcohol, tertiary butyl alcohol, and methylene etherwith from about 1 to about 28 parts of water to form a solvent-watermixture;

(2) adding from about 1 to about 20 parts of cellulose to thesolvent-water mixture to form a cellulosecontaining slurry;

(3) reacting the cellulose-containing slurry with from about 0.4 toabout 20 parts of an alkali metal hydroxide to form an alkalized slurry(4) adding a dye selected from the group consisting of and (4) sodium4(2H-naphtho (1,2-d)trazol-2-yl)-2-stilbene sulfonate to the alkalizedslurry of step (3) in an amount such that the ratio of the dye to thecellulose present in the slurry is in a range of from about 1:6 to about1:250 to form a dye-containing slurry; and

(5) reacting the dye-containing slurry with from about 0.4 to 2.5 molesof monochloroacetic acid per mole of cellulose whereby dyed alkali metalcarboxymethylcellulose is formed.

2. The process of claim 1 wherein the amount of dye added is in a ratioof dye to cellulose of about 1:10 to 1:150.

3. The process of claim 1 wherein the alkali metal is selected from thegroup consisting of potassium, sodium or lithium.

4. The process of claim 1 wherein the cellulose has a particle sizewhich permits it to pass through a Tyler standard screen of about 20 toabout 60 mesh.

NaOaS SOaNa;

References Cited UNITED STATES PATENTS 2,517,577 8/1950 Klug et a1260-231 1,886,480 11/1932 Haller 106193 D 2,448,515 9/1948 Carroll106193 D OTHER REFERENCES Chem. Abst. 57:1122 C, 1962.

THEODORE MORRIS, Primary Examiner US. Cl. X.R.

